package zct.proj.util;

public class CRC {

	// "CRC查表法"
    //  ;CRC-CCITT 的码表 高位
    private short[] CRCTableH = new short[] {0x0, 0x10, 0x20, 0x30, 0x40, 0x50, 0x60, 0x70,
				0x81, 0x91, 0xA1, 0xB1, 0xC1, 0xD1, 0xE1, 0xF1,
				0x12, 0x2, 0x32, 0x22, 0x52, 0x42, 0x72, 0x62, 
				0x93, 0x83, 0xB3, 0xA3, 0xD3, 0xC3, 0xF3, 0xE3, 
				0x24, 0x34, 0x4, 0x14, 0x64, 0x74, 0x44, 0x54, 
				0xA5, 0xB5, 0x85, 0x95, 0xE5, 0xF5, 0xC5, 0xD5, 
				0x36, 0x26, 0x16, 0x6, 0x76, 0x66, 0x56, 0x46, 
				0xB7, 0xA7, 0x97, 0x87, 0xF7, 0xE7, 0xD7, 0xC7, 
				0x48, 0x58, 0x68, 0x78, 0x8, 0x18, 0x28, 0x38, 
				0xC9, 0xD9, 0xE9, 0xF9, 0x89, 0x99, 0xA9, 0xB9, 
				0x5A, 0x4A, 0x7A, 0x6A, 0x1A, 0xA, 0x3A, 0x2A, 
				0xDB, 0xCB, 0xFB, 0xEB, 0x9B, 0x8B, 0xBB, 0xAB, 
				0x6C, 0x7C, 0x4C, 0x5C, 0x2C, 0x3C, 0xC, 0x1C, 
				0xED, 0xFD, 0xCD, 0xDD, 0xAD, 0xBD, 0x8D, 0x9D, 
				0x7E, 0x6E, 0x5E, 0x4E, 0x3E, 0x2E, 0x1E, 0xE, 
				0xFF, 0xEF, 0xDF, 0xCF, 0xBF, 0xAF, 0x9F, 0x8F, 
				0x91, 0x81, 0xB1, 0xA1, 0xD1, 0xC1, 0xF1, 0xE1, 
				0x10, 0x0, 0x30, 0x20, 0x50, 0x40, 0x70, 0x60, 
				0x83, 0x93, 0xA3, 0xB3, 0xC3, 0xD3, 0xE3, 0xF3, 
				0x2, 0x12, 0x22, 0x32, 0x42, 0x52, 0x62, 0x72, 
				0xB5, 0xA5, 0x95, 0x85, 0xF5, 0xE5, 0xD5, 0xC5, 
				0x34, 0x24, 0x14, 0x4, 0x74, 0x64, 0x54, 0x44, 
				0xA7, 0xB7, 0x87, 0x97, 0xE7, 0xF7, 0xC7, 0xD7, 
				0x26, 0x36, 0x6, 0x16, 0x66, 0x76, 0x46, 0x56, 
				0xD9, 0xC9, 0xF9, 0xE9, 0x99, 0x89, 0xB9, 0xA9, 
				0x58, 0x48, 0x78, 0x68, 0x18, 0x8, 0x38, 0x28, 
				0xCB, 0xDB, 0xEB, 0xFB, 0x8B, 0x9B, 0xAB, 0xBB, 
				0x4A, 0x5A, 0x6A, 0x7A, 0xA, 0x1A, 0x2A, 0x3A, 
				0xFD, 0xED, 0xDD, 0xCD, 0xBD, 0xAD, 0x9D, 0x8D, 
				0x7C, 0x6C, 0x5C, 0x4C, 0x3C, 0x2C, 0x1C, 0xC, 
				0xEF, 0xFF, 0xCF, 0xDF, 0xAF, 0xBF, 0x8F, 0x9F, 
				0x6E, 0x7E, 0x4E, 0x5E, 0x2E, 0x3E, 0xE, 0x1E};
    // CRC-CCITT 的码表 低位

    private short[] CRCTableL = new short[] {0x0, 0x21, 0x42, 0x63, 0x84, 0xA5, 0xC6, 0xE7, 
			    0x8, 0x29, 0x4A, 0x6B, 0x8C, 0xAD, 0xCE, 0xEF, 
			    0x31, 0x10, 0x73, 0x52, 0xB5, 0x94, 0xF7, 0xD6, 
			    0x39, 0x18, 0x7B, 0x5A, 0xBD, 0x9C, 0xFF, 0xDE, 
			    0x62, 0x43, 0x20, 0x1, 0xE6, 0xC7, 0xA4, 0x85, 
			    0x6A, 0x4B, 0x28, 0x9, 0xEE, 0xCF, 0xAC, 0x8D, 
			    0x53, 0x72, 0x11, 0x30, 0xD7, 0xF6, 0x95, 0xB4, 
			    0x5B, 0x7A, 0x19, 0x38, 0xDF, 0xFE, 0x9D, 0xBC, 
			    0xC4, 0xE5, 0x86, 0xA7, 0x40, 0x61, 0x2, 0x23, 
			    0xCC, 0xED, 0x8E, 0xAF, 0x48, 0x69, 0xA, 0x2B, 
			    0xF5, 0xD4, 0xB7, 0x96, 0x71, 0x50, 0x33, 0x12, 
			    0xFD, 0xDC, 0xBF, 0x9E, 0x79, 0x58, 0x3B, 0x1A, 
			    0xA6, 0x87, 0xE4, 0xC5, 0x22, 0x3, 0x60, 0x41, 
			    0xAE, 0x8F, 0xEC, 0xCD, 0x2A, 0xB, 0x68, 0x49, 
			    0x97, 0xB6, 0xD5, 0xF4, 0x13, 0x32, 0x51, 0x70, 
			    0x9F, 0xBE, 0xDD, 0xFC, 0x1B, 0x3A, 0x59, 0x78, 
			    0x88, 0xA9, 0xCA, 0xEB, 0xC, 0x2D, 0x4E, 0x6F, 
			    0x80, 0xA1, 0xC2, 0xE3, 0x4, 0x25, 0x46, 0x67, 
			    0xB9, 0x98, 0xFB, 0xDA, 0x3D, 0x1C, 0x7F, 0x5E, 
			    0xB1, 0x90, 0xF3, 0xD2, 0x35, 0x14, 0x77, 0x56, 
			    0xEA, 0xCB, 0xA8, 0x89, 0x6E, 0x4F, 0x2C, 0xD, 
			    0xE2, 0xC3, 0xA0, 0x81, 0x66, 0x47, 0x24, 0x5, 
			    0xDB, 0xFA, 0x99, 0xB8, 0x5F, 0x7E, 0x1D, 0x3C, 
			    0xD3, 0xF2, 0x91, 0xB0, 0x57, 0x76, 0x15, 0x34, 
			    0x4C, 0x6D, 0xE, 0x2F, 0xC8, 0xE9, 0x8A, 0xAB, 
			    0x44, 0x65, 0x6, 0x27, 0xC0, 0xE1, 0x82, 0xA3, 
			    0x7D, 0x5C, 0x3F, 0x1E, 0xF9, 0xD8, 0xBB, 0x9A, 
			    0x75, 0x54, 0x37, 0x16, 0xF1, 0xD0, 0xB3, 0x92, 
			    0x2E, 0xF, 0x6C, 0x4D, 0xAA, 0x8B, 0xE8, 0xC9, 
			    0x26, 0x7, 0x64, 0x45, 0xA2, 0x83, 0xE0, 0xC1, 
			    0x1F, 0x3E, 0x5D, 0x7C, 0x9B, 0xBA, 0xD9, 0xF8, 
			    0x17, 0x36, 0x55, 0x74, 0x93, 0xB2, 0xD1, 0xF0};
    /* <summary>
     * 查表法返回byte()高位在0字节,低位在1字节.
     * </summary>
     * <param name="Data">做CRC的数组从0开始</param>
     * <param name="DCount">需作CRC的字节数量</param>
     * <returns></returns>
     * <remarks></remarks>
     */
    public short[] CRCTable(short[] data, int dCount) {
    	short revCRCHi = 0;
    	short revCRCLo = 0;
    	int bytIndex;
    	
    	for (short i = 0; i < dCount; i++) {
    		bytIndex = revCRCLo ^ data[i];
            revCRCLo = (short) (revCRCHi ^ CRCTableH[bytIndex]);
            revCRCHi = CRCTableL[bytIndex];
    	}
        
    	return new short[] {revCRCLo, revCRCHi};
    }
}   
	

//public Class Decoder {
//
//	    /* <summary>
//	     * 输入数据进行转义解码，将 H10  H81 转义为H01,  H10  H83 转义为 H03   H10  H90 转义为 H10 
//	     * </summary>
//	     * <param name="Data">一字节必须为H1,尾字节必须为H3</param>
//	     * <returns></returns>
//	     * <remarks></remarks>
//	     */
//	public short[] decodeData(short[] data) {
//		ArrayList<?> dataR = new ArrayList<?>();
//
//		if (data == null || data.length == 0) {
//			return null;
//		}
//        //'判断数据头和尾格式是否正确。
//		if (data[0] != 0x1 && data[data.length - 1] != 0x3) {
//			return null;
//		}
//
////        '开始转义 将com1r中的数据转义存储到bytcrc数组中,对除去贞头和贞尾外的所有字节进行转义。
////        '转义前  0x10 0x81   0x10 0x83   0x10 0x90
////        '转义后    0x01        0x03        0x10
//
////        '从第数据长度字节开始至CRC字节做转义。
//
//		for (int k = 2; k < data.length - 2) {
//			if (data[k] )
//		}
//        For K As Integer = 2 To Data.Length - 2
//            If Data(K) = 0x10 Then
//                Select Case Data(K + 1)
//                    Case Is = 0x81
//                        DataR.Add(0x1)
//                        K += 1
//                    Case Is = 0x83
//                        DataR.Add(0x3)
//                        K += 1
//                    Case Is = 0x90
//                        DataR.Add(0x10)
//                        K += 1
//                End Select
//            Else
//
//                DataR.Add(Data(K))
//
//            End If
//        Next
//        '定义返回字节数组
//        Dim ReturnData(DataR.Count - 2) As Byte
//
//        For X As Integer = 1 To DataR.Count - 1
//            ReturnData(X - 1) = DataR(X)
//        Next
//
//        Dim RBytes(ReturnData.Length + 1) As Byte
//
//        RBytes(0) = 0x1
//        For X As Integer = 0 To ReturnData.Length - 1
//            RBytes(X + 1) = ReturnData(X)
//        Next
//        RBytes(RBytes.Length - 1) = 0x3
//
//        Return RBytes
//	}
//}
